Transcript lens

Lens diseases
Wen Xu
Eye Center, 2nd Affiliated Hospital
Zhejiang University
The most common cause
of painless, progressive
loss of vision today is
Cataract
Anatomy of the lens
Location
posterior to iris
anterior to vitreous
 Shape biconvex
 Structure
lens capsule
lens cortex
lens nucleus

Physiology of the lens

No vessel, nerve and transparent.

Derive nutrients from the aqueous humor

Significant refractive medium

Accommodative function

No immediate relation with adjacent tissues

Complex metabolism

Simple disorders: transparency and location change
Cataract
 Definition:
opacification of the lens
 epidemiology:
clinical cataract
corrected vision<0.5
Cataract
Mechanism:
many factors
lens capsular damage
osmosis increase,loss of protective
screen,metabolic disorders
protein
degeneration, cell apoptosis
lens opacify
cataract
Cataract
Classification:

by cause: congenital, senile(age-related), complicated,
metabolitic, drug-induced, toxic, traumatic, secondary

by age:congenital, acquired

by location: cortical, nuclear, subcapsular

by shape: dot-like, coronary, lamellar

by degree: immature, intumescent, mature, hypermature
Cataract
Symptoms:

decreased vision: most obvious and important

decreased contrast sensitity

refractive error: myopia,astigmatism

monocular diplopia or multiple vision

glare: scattered light rays

poor color discrimination:blue spectrum
Cataract
Signs:
The lens is best examined with the pupil
dilated. A magnified view of the lens can be
obtained with a slit-lamp or by using the direct
ophthalmoscope with a high plus (10+) setting
Cataract
Grade’s standards of nuclear hardness:
Ⅰ transparent,no nucleus,soft
Ⅱ yellow-white or yellow,soft
Ⅲ dark yellow,moderate hard
Ⅳ brown or amber, hard
Ⅴ brown or black,extremely hard
(I) Age-related cataract
Description:
the most common type, most patients are beyond
their 50’s. The incidence goes up with aging. It is the
first rank of ophthalmic diseases leading to blindness
Risk factors:
Many factors are involved include age, occupation,
sex, ultraviolet radiation, diabetes, hypertension,
positive family history, nutritious condition
(i) Cortical Cataract
 The
most common type
 Four
stages:
(1) incipient stage
(2) intumescent stage or immature stage
(3) mature stage
(4) hypermature stage
1. incipient stage
Features:
a、cuneiform(楔形['kjunɪə,fɔrm]) opacity
b、lamellar seperate
c、vacuole
d、cracks
e、no vision damage
Tests: a、slit-lamp b、transillumination
2. intumescent stage or
immature stage
Features:
a、more serious opacity
b、larger volume and more shallow anterior
chamber
c、iris shadow
d、obvious vision decrease
e、myopia
Tests: a、slit-lamp b、oblique illumination
Matter needs attention: angle-closure glaucoma
3. mature stage
Features:
a、complete opacity, milky white, iris shadow
disappear
b、volumn and anterior chamber regain normal
c、vision: LP or HM before the eye
Tests: a、slit-lamp
b、flashlight
4. hypermature stage
Features:
a、smaller volumn,wrinkled lens capsule,claybank
and fallen nucleus (Morgagnian cataract) ,superior
of anterior chamber deepens while inferior is the
opposite,ridodonesis.
b、laceration of lens capsule,lens luxation.
c、phacoanaphylactic uveitis,phacolytic glaucoma
(ii) Nuclear Cataract
Features:
a、start earlier,generally on 40’s,slowly
progressive, not likely to be mature.
b、nuclear opacity: start by embryonic nucleus.
c、vision: no vision damage early on, myopia
Tests: slit-lamp、 transillumination、 oblique
illumination
(iii) Subcapsular Cataract
Features:
a、start earlier
b、posterior subcapsular cataract: cause
obvious vision defect early on
c、cupuliform(杯状) opacity of posterior pole
(II) Congenital Cataract
Features:
present at birth or appear shortly thereafter; unilateral or bilateral;
may be alone or associated with other ocular or systemic
congenital abnomalities
Etiology:
(1) hereditary factors(chromosome,gene)
(2) environmental factors (matrix disease) when pregnance <3 m:
virus infection; drugs,metabolic diseases
(3) undetermined causes
Classification
According to location, form and degree

anterior polar cataract

posterior polar cataract

perinuclear cataract

coronary cataract

punctate cataract

total cataract

membrane cataract

nuclear cataract
Congenital cataract
Anterior polar cataract
Posterior polar cataract
Perinuclear cataract
Coronary cataract
Punctate cataract
Total cataract
Membrane cataract
Nuclear cataract
(III) complicated cataract
Features:
ocular inflammation or degenerative disorders→
nutritious or metabolic defect → lens opacity
Common causes:
corneal ulcer, glaucoma, uveitis,retinal
detachment, retinitis pigmentosa, intraocular
tumor,high myopia, etc.
Clinical findings:
1. primary disease changes
2. cataract
Treatment:
1. treat the primary disease.
2.do the surgery after 3 m of
inflammation control
(IV) Metabolic cataract
 Diabetic
cataract
 Galactose cataract: lack of enzyme
 Tetany cataract: low blood calcium
 Wilson’s disease (Hepatolenticular
Degeneration): KF ring, sunflower-shaped
opacity,copper.
1. Diabetic cataract
 Mechanism:
blood sugar↑ →sugar in the lens↑ → change
into sorbitol→plasma osmotic pressure↑
→absorb water→fibers swellen and
degenerate→lens opacity
 classification:
(1) real diabetic cataract
(2) age-related cataract of diabetic patients
 Clinical
findings:
(1) the first type: teenagers,bilateral,rapidly
progressive,eading to total cataract,combined
with refractive changes according to blood sugar
(2) the second type: high incidence,start earlier, fast
progressive, easy to be mature,similar with
senile cortical cataract
 Treatment:
(1) positively treat diabetes,control blood
sugar
(2) do the surgery if permitted
(3) positively postoperational infection and
bleeding prevention
(V) Drug-induced and toxic
cataract

Corticosteroid cataract

Chlorpromazine cataract

Miotic cataract

Trinitrotoluence cataract

Metals
Trinitrotoluence cataract
(VI) Traumatic cataract
 Classification:
Contusive cataract
Penetrating cataract
Chemical injuries cataract
Radiation cataract
Electric cataract
 Treatment: observation or surgery
(VII) Secondary cataract
 Definitions:
opacification of the posterior capsule due to partially
absorbed traumatic cataract or following extracapsular
cataract extraction (posterior capsular opacification). It
is the most common complication of cataract surgery
 Clinical
findings:
vision decrease after cataract surgery;
Elschnig’s pearls

It is a significant problem in almost all pediatric
patients unless the posterior capsule and anterior
vitreous are removed at the time of surgery. Up to
30%-50% of all adult patients develop an opaque
secondary membrane after cataract surgery
 Treatment:
neodymium:YAG capsulotomy
Treatment of cataract

There are many kinds of medicines,but none
has certain positive effect

Surgery is the chief method
Surgical treatment
 Timing
of the surgery:
a、mature stage→visual acuity
b、consider the surgery conditions and the
subjective requirements of patients
 Preoperative

Examination & preparation
Ocular: VA,LP,color vision,anterior
segment,fundus,IOP,SLE ,EKG,VEP,ultrasonic,etc.
 System:BP,blood sugar,etc.
 Corneal curvature,the axial length of the
eye.calculate the diopter of the IOL
 Endothelial cell acount (specular microscopy)
 Wash conjunctival sac and lacrimal canal,dilate the
pupil
Way of the surgery

Couching(针拨) of lens

Intracapsular cataract extraction (ICCE)

Extracapsular cataract extraction (ECCE)

Phacoemulsification (PHACO)

Laseremulsification

Intraocular lens implantation
Surgical complications
 Complications
during the surgery
(1)shallow or no anterior chamber
(2)intraocular tissue lesion
(3)hemorrhage
(4)posterior capsular rupture
 Postoperational
complication
(1)hemorrhage
(2)high IOP
(3)endophthalmitis
(4)chronic uveitis
(5)posterior capsular opacification
(6)corneal astigmatism
(7)retinal phototoxicity
(8)cystoid macular edema, CME
 Postoperational
complications of IOL
implantation
(1)pericorneal fibrous proteins exudation
(2)dislocation of IOL
(3)secondary glaucoma and decompensation of
corneal endothelium
(4)diopter inaccuracy of IOL
Refractive correction of aphakia

IOLs :Multifocal, Accommodatable

Spectacles

Contact lens

Refractive surgeries: keratophakia,
keratomileusis, epikeratophakia
Dislocated lens or ectopia lentis
 Causes
(1) congenital
simple dislocation; combined with lens or ocular
abnormalities; systemic syndromes (Marfan syndrome,
homocystinuria, Marchesani syndrome, Ehlers-Danlos
syndrome)
(2) traumatic
(3) spontaneous
 Clinical
findings
(1) Partial dislocation:
the edge of the lens and the zonular fibers holding it in
place can be seen in the pupil. It is often complicated by
deepen anterior chamber,iridodonesis and vitreous
hernia. High myopia and monocular diplopia,or even
secondary glaucoma may occur
(2) Complete dislocation:
include pupil entrapment,dislocated into anterior
chamber, dislocated into vitreous cavity,dislocated into
subconjunctiva or even extraocular
 complications
(1)Uveitis
(2)Secondary glaucoma
(3)Retinal detachment: the most common
(4)Corneal opacification
 Treatment
(1) nonsurgical therapy:
If no complications, dislocated lenses are best left
untreated. Close conservation and spectacles or
contacts may have some value
(2) surgical therapy:
If uveitis or uncontrollable glaucoma occurs, lens
extraction must be done. The technique of choice is
limbal or pars plana lensectomy using a motor-driven
lens & vitreous cutter
Dislocated in anterior chamber
Partial dislocation
Partial dislocation